1. Field of the Invention
The subject invention relates primarily to the art of dentistry and, more specifically, to methods, apparatus and instruments for removing bridges, full and partial crowns, inlays, including one and two surface inlays, onlays and similar dental restorations from patients' teeth without injury to or impairment of such teeth and, typically, without injury to the removed restoration.
2. Prior Art Statement
A well-known type of crown and bridge remover uses a pair of tongs for gripping a crown or bridge abutment. In one form of execution, one of the tongs is provided with an aperture for accommodating a hook with which forces are exerted on the remover by the dentist. In practice, the dentist frequently has to exert a hammering action on that type of remover to make it work. For this purpose, there exists an inertia type of hammer with which the remover with engaged crown or bridge is hammered away from the teeth.
Unfortunately, such harsh procedure often eventuates dislocation of, damage to or even loss of the underlying tooth.
Another tong-type of crown and bridge remover employs a threaded pin which is brought to bear upon the tooth through a hole drilled into the occlusal surface of the crown or bridge abutment to be removed.
In practice, this remover, as well as the other tong-type remover previously mentioned herein, is restricted in its utility to the removal of full crowns or bridge abutments which can be firmly gripped by a pair of tongs. Even then, the necessity of the tong having to establish a firm grip at the cervical portion of the crown often eventuates damage to the gum or tooth at the cervical line or discomfort to the patient.
Another kind of remover which does not rely on a tong-type engagement comprises a conical screw with a hexagonal or square head and a wrench for engaging that head. A hole suitable for tapping by the screw is drilled into the occlusal surface of the crown to be removed. A thread is then cut into the crown at the hole with the screw actuated by the wrench. In the course of the threading operation the tip of the screw will come to bear on the underlying tooth and further turning of the screw tends to lift the crown away. An advantage of this procedure is that it can be used not only on crowns, but also on inlays which could not be gripped by tongs.
However, the utility of the latter screw-type remover is still limited to relatively heavy crowns and inlays of sufficient thickness to permit an effective thread cutting action by the screw. Also, the necessarily relatively sharp tip of the conical tapping screw has a tendency to split or otherwise damage the underlying tooth structure.
In consequence, there are many situations wherein resort has to be had to one of the cruder procedures for removing bridges, crowns, inlays and onlays, involving the use of hook-like or other force-applying instruments and hammers, frequently damaging the underlying tooth or otherwise discomforting the patient.